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U.S. Global Change Research Program
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The U.S. Global Change Research Program (USGCRP) is a federal program mandated by Congress to coordinate federal research and investments in understanding the forces shaping the global environment, both human and natural, and their impacts on society. USGCRP facilitates collaboration and cooperation across its 13 federal member agencies to advance understanding of the changing Earth system and maximize efficiencies in federal global change research.
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Climate Change Impact: Food Systems, Food Security, and Global Linkages
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Food systems both impact and are affected by climate change. Emissions come not only from farming, but also from the processing, manufacturing, distribution, storage, sale, and preparation of food, and the disposal of food wastes. Likewise, climate change influences not just agriculture, but activities that occur throughout this larger system. In this talk, Dr. Peters will address the fundamental concepts of food systems and food security. He will explain how scientists estimate climate emissions from individual supply chains and from whole food systems. He will also consider case study examples of strategies for reducing emissions viewed both from the production and consumer ends of the food system.
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Technical Mitigation Options in Forests
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Dr. Richard A. Birdsey, a Senior Scientist with the Woodwell Climate Research Center, discusses the forest carbon cycle, the role of U.S. forests in mitigating climate change and helping the U.S. meet its 2050 net zero greenhouse gas emissions goal, and how conditions in the future may impact this critical carbon sink.
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Greenhouse Gases in Agriculture and Forests
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Dr. Grant Domke and Dr. Charles W. Rice discuss trends in GHG emissions over time, U.S. land sector GHG emissions and removals, the GHG emission intensity of agricultural commodities, and opportunities to reduce emissions and enhance soil carbon sequestration.
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Climate: Sawyer predicted rate of warming in 1972
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Excerpt: "In four pages Sawyer summarized what was known about the role of carbon dioxide in enhancing the natural greenhouse effect, and made a remarkable prediction of the warming expected at the end of the twentieth century.He concluded that the 25% increase in atmospheric carbon dioxide predicted to occur by 2000 corresponded to an increase of 0.6 °C in world temperature..... In fact the global surface temperature rose about 0.5 °C between the early 1970s and2000. Considering that global temperatures had, if anything, been falling in the decades leading up to the early 1970s, Sawyer’s prediction of a reversal of this trend, and of the correct magnitude of the warming, is perhaps the most remarkable long-range forecast ever made.
Despite huge efforts, and advances in the science, the scientific consensus on the amount of global warming
expected from increasing atmospheric carbon dioxide concentrations has changed little from that in Sawyer’s time.
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Are there basic physical constraints on future anthropogenic emissions of carbon dioxide?
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Here, it is shown both theoretically and observationally how the evolution of the human system can be considered from a surprisingly simple thermodynamic perspective in which it is unnecessary to explicitly model two of the emissions drivers: population and standard of living. Specifically, the human system grows through a self-perpetuating feedback loop in which the consumption rate of primary energy resources stays tied to the historical accumulation of global economic production—or p × g—through a time-independent factor of 9.7 ± 0.3 mW per inflation-adjusted 1990 US dollar. This important constraint, and the fact that f and c have historically varied rather slowly, points towards substantially narrowed visions of future emissions scenarios for implementation in GCMs.
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Carbon debt and carbon sequestration parity in forest bioenergy production
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The capacity for forests to aid in climate change mitigation efforts is substantial but will ultimately depend on their management. If forests remain unharvested, they can further mitigate the increases in atmospheric CO2 that result from fossil fuel combustion and deforestation. Alternatively, they can be harvested for bioenergy production and serve as a substitute for fossil fuels, though such a practice could reduce terrestrial C storage and thereby increase atmospheric CO2 concentrations in the near-term. Here, we used an ecosystem simulation model to ascertain the effectiveness of using forest bioenergy as a substitute for fossil fuels, drawing from a broad range of land-use histories, harvesting regimes, ecosystem characteristics, and bioenergy conversion effi- ciencies. Results demonstrate that the times required for bioenergy substitutions to repay the C Debt incurred from biomass harvest are usually much shorter (< 100 years) than the time required for bioenergy production to substitute the amount of C that would be stored if the forest were left unharvested entirely, a point we refer to as C Sequestration Parity. The effectiveness of substituting woody bioenergy for fossil fuels is highly dependent on the factors that determine bioenergy conversion efficiency, such as the C emissions released during the har- vest, transport, and firing of woody biomass. Consideration of the frequency and intensity of biomass harvests should also be given; performing total harvests (clear-cutting) at high-frequency may produce more bioenergy than less intensive harvesting regimes but may decrease C storage and thereby prolong the time required to achieve C Sequestration Parity.
Keywords: bioenergy, biofuel, C cycle, C sequestration, forest management
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A new, global, multi-annual (2000–2007) burnt area product at 1 km resolution Vol. 35
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This paper reports on the development and validation
of a new, global, burnt area product. Burnt areas are
reported at a resolution of 1 km for seven fire years (2000 to
2007). A modified version of a Global Burnt Area (GBA)
2000 algorithm is used to compute global burnt area. The
total area burnt each year (2000– 2007) is estimated to be
between 3.5 million km2 and 4.5 million km2
. The total
amount of vegetation burnt by cover type according to the
Global Land Cover (GLC) 2000 product is reported.
Validation was undertaken using 72 Landsat TM scenes
was undertaken. Correlation statistics between estimated
burnt areas are reported for major vegetation types. The
accuracy of this new global data set depends on vegetation
type.
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A holistic approach to climate targets
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An assessment of allowable carbon emissions that factors in multiple climate targets finds smaller permissible emission budgets than those inferred from studies that focus on temperature change alone.
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Delayed detection of climate mitigation benefits due to climate inertia and variability
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Climate change mitigation acts by reducing greenhouse gas emissions, and thus curbing, or even reversing, the increase in their atmospheric concentration. This reduces the associated anthropogenic radiative forcing, and hence the size of the warming. Because of the inertia and internal variability affecting the climate system and the global carbon cycle, it is unlikely that a reduction in warming would be immediately discernible. Here we use 21st century simulations from the latest ensemble of Earth System Model experiments to investigate and quantify when mitigation becomes clearly discernible. We use one of the scenarios as a reference for a strong mitigation strategy, Representative Concentration Pathway (RCP) 2.6 and compare its outcome with either RCP4.5 or RCP8.5, both of which are less severe mitigation pathways. We analyze global mean atmospheric CO2, and changes in annually and seasonally averaged surface temperature at global and regional scales. For global mean surface temperature, the median detection time of mitigation is about 25–30 y after RCP2.6 emissions depart from the higher emission trajectories. This translates into detection of a mitigation signal by 2035 or 2045, depending on whether the comparison is with RCP8.5 or RCP4.5, respectively. The detection of climate benefits of emission mitigation occurs later at regional scales, with a median detection time between 30 and 45 y after emission paths separate. Requiring a 95% confidence level induces a delay of several decades, bringing detection time toward the end of the 21st century.
regional climate change | climate variability | signal detection
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